/*
 * Copyright (c) 2009 Communication Group and Eislab at
 * Lulea University of Technology
 *
 * Contact: Laurynas Riliskis, LTU
 * Mail: laurynas.riliskis@ltu.se
 * All rights reserved.
 *
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the
 *   distribution.
 * - Neither the name of Communication Group at Lulea University of Technology
 *   nor the names of its contributors may be used to endorse or promote
 *    products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL STANFORD
 * UNIVERSITY OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * Implementation of the HIL required micro busy wait.
 * For more information see TEP 102.
 *
 * @author Henrik Makitaavola <henrik.makitaavola@gmail.com>
 */
module BusyWaitMicroC
{
  provides interface BusyWait<TMicro, uint16_t>;
}
implementation
{
  // TODO(henrik) This will now only work on 10Mhz speed, easy to
  //              add a signal from the control module of the mcu
  //              to signal the change of speed and the wait function
  //              can adjust to it.
  // The wait function can not be inlined because then the code alignment may
  // go lost thus making the busy wait around 30% slower.
  async command void BusyWait.wait(uint16_t dt ) __attribute__((noinline)) {
    atomic {
      asm("nop"); // Nop needed to align function
      asm volatile (
          "sub.w #1,%[t]\n\t"
          "jeq 2f\n\t"
          "sub.w #1,%[t]\n\t"
          "jeq 2f\n\t"
          "1:\n\t"
          "nop\n\t"
          "add.w #1,%[t]\n\t"
          "sub.w #1,%[t]\n\t"
          "sub.w #1,%[t]\n\t"
          "jgtu 1b\n\t"
          "2:"
          :   
          : [t] "r" (dt)
          );  
    } 
  } 
}
